1. Field of the Invention
The present invention relates generally to image sensors, and more particularly, to an image sensor having increased efficiency in conversion of received light.
2. Background of the Invention
A photoelectric converter is formed in a silicon (Si) area that absorbs light in a visible spectrum within an image sensor such as a CMOS (complementary metal oxide semiconductor) image sensor (CIS) or a charge-coupled device (CCD). Light having a wavelength in a shorter wavelength range is absorbed by Si at a greater rate such that most of such light is absorbed by the photoelectric converter.
However, as the wavelength of light increases, the absorption rate of such light by Si decreases. In particular, a photoelectric converter having a limited depth just passes most of light having a wavelength in a longer wavelength range resulting in decreased conversion efficiency and thus decreased sensitivity.
Moreover, charge carriers such as electrons generated at a deep region in a lower portion of a photoelectric converter of a pixel diffuse to photoelectric converters of other adjacent pixels resulting in crosstalk between pixels.